The objective of the proposed research is to examine the demographic impact of trends in "early" and "late" motherhood. Early mothers are defined as women who have their first birth before age 20, and late mothers are women who have their first after age 25. Based on vital statistics mortality and fertility data from 1917-1980, available by race, we propose to develop a model of fertility to estimate the percentage of all children in each year born to mothers who had their first birth before age 20, the percentage of all children in each year born to mothers who had their first birth after age 25, the distribution of children by family size, and the percentage of a cohort's completed fertility accounted for by early and late mothers. The single-year series of distributions resulting from the research should be of interest to other researchers and policy makers and efforts will be made to put these series in the public domain.